The first version of Duoheart let you see your partner's answer as soon as they wrote it. It felt efficient. It also killed the entire point.
The moment you can see the other answer forming, you start writing toward it - softening an honest answer into an agreeable one, or performing for an audience of one. Blind answering removes that audience. You write for yourself first.
Both answers lock the instant both are in, and unlock to each other at the exact same moment. Neither of you got to see the other's answer before committing to your own. That small mechanical constraint is what makes the daily question actually honest.
It's a small thing. It changes everything about what people are willing to write.